Rename them so they end in txt instead of cfg, then use the exec
console command. For example, if you rename it addons.txt, you would run exec addons.txt
.
If you wanted to get fancy, you could then create a new autoexec.cfg that contains nothing but alias launchaddons "exec addons.txt"
. This basically lets you add a custom console command; you would just run launchaddons
in the console and your commands in addons.txt would run.
Check the wiki article on console commands for more info.